Methods for producing amino acid-modified organopolysiloxanes can be exemplified by a method in which an N-acylamino acid is reacted in a polar aprotic solvent with an organopolysiloxane that contains a halogenated alkyl group in the molecule (refer to JP 50-158700 A); a method in which an amino acid is reacted in the presence of an acid catalyst with organopolysiloxane that has a carbon-bonded hydroxyl group in the molecule (refer to JP 52-003023 A); and a method in which a carboxy-protected amino acid is reacted with an organopolysiloxane that has an epoxy group in the molecule (refer to JP 52-114699 A).
However, a problem with the methods provided in JP 50-158700 A and JP 52-003023 A is that no carboxy group of amino acid origin remains in the obtained amino acid-modified organopolysiloxane due to the reaction of the carboxy group in the amino acid, resulting in an inability to impart the properties characteristic of amino acids to this organopolysiloxane. The method provided in JP 52-114699 A requires that the carboxy group of the amino acid be protected as an alkali metal salt or ester, and also requires removal of the alkali metal or alcohol from the reaction product.
Moreover, while the use of amino acid-modified organopolysiloxane as a surfactant is disclosed in JP 50-158700 A, JP 52-003023 A, and JP 52-114699 A, there is no recognition therein with regard to the function of the amino acid-modified organopolysiloxane itself as a beautifying agent.